Sources told the Sunday Times the party had invited the Kenyan politician to the congress as a special guest.
"The party is inviting Dr Odinga to come and open our congress and conduct public sessions on democracy and social justice," said the source, who is involved in the consultations with the Kenyan premier.
He said the office of the party’s secretary-general Tendai Biti had been tasked with organising Odinga’s visit.
Tsvangirai, like his Kenyan counterpart, was forced into a government of national unity with his long-time rival President Robert Mugabe.
Odinga was forced into Africa’s first political marriage of convenience with incumbent Mwai Kibaki.
Because of their similar circumstances Odinga and Tsvangirai now view each other as democratic friends, and claim they were robbed of the presidency in previous elections held in their respective countries.
Biti was not reachable on his cellphone when contacted for comment.
However, his party’s spokesman Nelson Chamisa confirmed there were plans to invite the charismatic Kenyan prime minister to the congress.
"It’s too early because we haven’t even spoken to him but the plans are there," said Chamisa.
Odinga’s spokesman Dennis Onyango would neither confirm nor deny reports that his boss would be in Bulawayo in May.
"I will have to check," said Onyango by phone from the Kenyan capital Nairobi.
Odinga remains one of the few open critics of Mugabe on the continent, along with Archbishop Desmond Tutu of South Africa, Nigeria’s Wole Soyinka, the late Zambian president Levy Mwanawasa , Botswana leader Ian Khama and former UN secretary general Kofi Annan, who have called for the 87-year-old leader to step down